The method and apparatus of the present invention are useful for aiding restorative dentists and oral surgeons in the making of teeth prostheses.
To facilitate an understanding of the present invention, a brief overview of dental implant techniques may be useful. The overview is intended to be general in nature and cannot attempt to describe all the complexities of the art and science of dentistry and oral medicine.
As used herein, the terms apical and occlusal denote positions with respect to features of a patient's teeth. Apical suggests towards the root and occlusal suggests toward the chewing and biting surfaces of the teeth.
The terms "linqual" and "buccal" also denote positions with respect to the patient's teeth. Linqual denotes toward the tongue. Buccal denotes towards the cheek.
It is the practice of the resotrative dentists and oral surgeons to make a first impression of the surface features of an area in which a dental implant is to be placed. The impression is used to make a first cast. The first cast records the surface features in a form which the dentist or surgeon can readily plan future surgery, plan the placement of abutments and the type of tooth prosthesis.
Dental implantations are performed in stages. In the first stage, surgery would be performed to expose the bone, drill a cavity in the bone, and position an implant in the cavity. Implants are available in a variety of shapes and sizes.
Generally, implants are cylindrical in form having a circular occlusal surface. The occlusal surface will normally have a threaded opening to receive a screw for securing an abutment, or to receive an abutment having a corresponding threaded section. The abutment will be fitted at a later stage. A screw is normally placed in the hole as a cap during the healing process.
To facilitate securing the implant into bone and to provide alignment surfaces for abutments to be placed on the implant, some implants have keyed occlusal surfaces. On such keyed surface commonly used is a hexagonal extension of the implant.
The oral surgeon completes the first stage of surgery by closing the open surgical wound with stitches and the like, over the implant. The oral surgeon may note the location of the implant on the first cast.
Normally, the patient will not revisit the oral surgeon for three to six months. Three to six months are required for healing, to allow the implant to be securely received in the bone tissue. During the time in which the bone is receiving the implant, the original incisions in the soft tissue are healing, obscuring the location of the implant.
Three to six months after the first stage surgery, in the second stage of surgery, the oral surgeon will expose the implant to mount a temporary healing abutment. The temporary healing abutment brings the restorative surface to the crest of the gum to facilitate tissue healing. The oral surgeon may use the first cast to facilitate locating the implant. However, the exact position of the implant, its alignment, angle and position on the horizontal and vertical axis cannot be accurately placed on the surface features of the cast.
Upon completion of the second stage of surgery, the oral surgeon will secure the soft tissue with stitches, if necessary, and gauze. Oral surgeons rarely construct prosthetic teeth beyond the placement of the abutment. Typically, the oral surgeon will refer the patient to a restorative dentist.
A patient waits ten to fourteen days for healing following the placement of the temporary healing abutment to visit the restorative dentist for the first time. The patient will likely visit the restorative dentist four times.
During the patient's first visit, the restorative dentist will evaluate whether the abutment placed by the oral surgeon is suitable for a permanent prosthesis. The restorative dentist will remove the temporary healing abutment and place an impression coping on the implant. The impression coping has a cylindrical shape and is capable of being received on the implant by screws and the like. With the impression coping in place, the restorative dentist will make an impression of the surface features and the impression coping.
The impression coping is then removed from the implant. A cast of the impression is made with the impression coping and an implant analog fitted to the impression.
During the same first visit, the restorative dentist may fit a temporary crown, bridge, or tooth of acrylic material to protect the area of the future permanent prosthesis and to provide a better cosmetic appearance for the patient.
After the patient's first visit, the restorative dentist will make a diagnostic cast from the final impression. The restorative dentist will secure an implant analog to the impression coping. With the impression coping carried in the hole created when the impression was made, plaster will be poured into the impression. The diagnostic cast gives the location of the abutment or implant within the context of the surface features of the patient's mouth.
With the diagnostic cast, the restorative dentist will make a permanent abutment selection. The permanent abutment is ordered for placement in the patient's mouth at the next visit.
At the second visit, the restorative dentist secures the permanent abutment to the implant. The restorative dentist will confirm by X-ray that the permanent abutment is seated. The restorative dentist will also make a final impression.
The final impression is made with a further impression coping secured to the abutment. From the final impression, a final cast is made. An impression coping secured to an abutment analog is fitted to the impression and plaster poured into the final impression to form the final cast. The impression coping is removed to reveal an abutment analog secured in the final cast in the same respective position as the abutment in the patient's mouth.
The final cast is most often made in a dental laboratory from the final impression. With the final cast as a guide, the dental laboratory will fabricate a tooth prosthesis.
The tooth prosthesis is sent to the restorative dentist. At a third visit, the restorative dentist will temporarily mount the tooth prosthesis to the abutment to insure the tooth prosthesis fits with other teeth and features of the patient's mouth. The tooth prosthesis is then returned to the dental lab to be completed. After the dental laboratory completes the tooth prosthesis, it is sent back to the restorative dentist. The patient returns to the restorative dentist and the tooth prosthesis is permanently mounted to the abutment. The entire process of replacing a tooth may take nine months.
The long nine month period and repeated visits to the oral surgeon and the restorative dentist discourages patients from engaging in implant dentistry. Each visit to the oral surgeon and restorative dentist may produce uncomfortable experiences for patients, and increases the opportunities for patients to reevaluate their interest in having a tooth prosthesis.
A shorter period of time between the initiation of oral surgery and the fitting of a final tooth prosthesis would be more convenient, shorten periods of discomfort and provide improved cosmetic appearance and dental function for the patient. A reduction in the number of visits to oral surgeons and restorative dentists may reduce the cost of restorative dentistry.